This invention relates to mat-shaped heat exchangers employing such heat exchanging fluid as hot water caused to flow therethrough and, more specifically, to a heat exchange mat formed into a flat sheet shape for laying on a floor so as to achieve, for example, floor surface heating with hot water circulated throughout the interior of the mat.
Conventional apparatuses for exchanging heat of a fluid with room air could be disposed only at a corner part of a house room and their heat exchanging efficiency has been insufficient. For this reason, there have been recently developed such flat heat exchange mats that can be laid on a floor or wall surface for exchanging heat with the room air to improve the heat exchanging efficiency. In this case, the heat exchange mat comprises, as shown in FIG. 1, a heat exchanging element 1 of wavy warp and linear weft filaments 2 and 3 of a metal or plastic material and knitted with each other substantially perpendicularly, and a face sheet 5 made of a polyvinyl chloride or the like and bonded to each of top and bottom faces of the element 1 with such an insert 4 as a textile material interposed between them. In firmly bonding the face sheet 5 with the interposed insert 4 to the heat exchanging element 1, usually, a roll pressing force must be applied at least to one of the face sheets 5 so that the force will cause the element 1 to be once compressed to fall down to become smaller in thickness. While the original state of the element 1 can be substantially restored from this compressed state with the restoring force of the filaments specifically when hot water or the like heat exchanging fluid is fed to flow through passages 6 defined between the top and bottom inserts 4, it has been known that the linear weft filaments 3 are caused to be bent downward at their one longitudinal end part and upward at the other end part so that the mat will be wavy at opposing side edges in opposite upward and downward directions as shown in FIG. 2, whereby a problem is caused to arise in that the upward and downward bent edges of the mat laid on the floor give to a user walking on the mat a danger of false step.
On the other hand, there has been suggested in U.S. Pat. No. 4,230,175 a heat exchange mat provided as a flexible sheet adapted to be laid on a flat surface and to be applied to solar water-heater. This mat is provided, however, at both opposing side edges with heat-exchanging-fluid supplying and discharging members which are larger in thickness than the mat itself so that the mat laid on a room floor may also give to the user the same danger of false step at the higher fluid supplying and discharging members. For this reason, too, it has been demanded to provide a heat exchange mat which is evenly flat without any rising part.